Patients with quadriplegia, muscular dystrophy, and other forms of neuromuscular disease demonstrate significant abnormalities in chest wall and lung mechanics which are attributed to ventilatory muscle weakness. These abnormalities place these patients at significant risk to develop life-threatening respiratory complications. Previous investigators have described a reduction in chest wall compliance in patients with neuromuscular weakness. This finding is attributed to an inability to fully expand the chest which leads to stiffening of the joints and tissues of the rib cage. Patients with chest wall muscle weakness also have reduced lung compliance. This is explained by atelectasis or an increase in the surface tension of the alveolar lining layer resulting from breathing at low lung volume.
A reduction in lung and chest wall compliance is also seen with kyphoscoliosis. Sinha and Bergofsky demonstrated that hyperinflation with intermittent positive pressure breathing (IPPB) for five minutes at 22 cm HsO pressure increased dynamic lung compliance up to 70 percent above baseline values and the effect lasted for as long as three hours. Thus, by increasing lung compliance, the work of breathing decreases, and respiratory failure may theoretically be averted.